Speeduino

What rpm do you get while cranking with basic distributor? Rather high I suspect.
I think basic distributor decoder will get sync against pretty much any signal pattern - every 2 teeth look like a rev to it.

+1, and it should sync with anything (with sync loss occasionally), but won't run like that of course. However, this proves the hardware and Speeduino are functional, but confused.

So the search now is for what signal the ECM is seeing, compared to what it is expecting. Refer to the previous comments where a 'scope trace should reveal what the signal is at the processor, and if it complies with the pattern selected in TunerStudio. They are like two puzzle pieces that must fit. Simple stuff like sensor polarity or Trigger Edge can upset the pattern.

PSIG wrote: ↑Sun Jun 04, 2023 3:16 pm +1, and it should sync with anything (with sync loss occasionally), but won't run like that of course. However, this proves the hardware and Speeduino are functional, but confused.

So the search now is for what signal the ECM is seeing, compared to what it is expecting. Refer to the previous comments where a 'scope trace should reveal what the signal is at the processor, and if it complies with the pattern selected in TunerStudio. They are like two puzzle pieces that must fit. Simple stuff like sensor polarity or Trigger Edge can upset the pattern.

Hi,
If you check few posts back I attached two photos of crank sensor vs. ECU conditioned signal. (Attaching screen shot of them)

I know that a 60-2 signal should show 58 spikes then a longer flat section, but while cranking and watching the scope, I get a spike per engine rev, so my sensor behaves like one tooth, if that makes any sense. I’ll attach a pic of that sensor with its part No.

I will take a picture of the trigger wheel too for your reference

Ah, OK, so you're reading 1 Tooth per rev - I missed that.
Are you sure that the sensor isn't reading something other than the trigger wheel? Is there a fan blade rotating at that rate or something? Or has the trigger wheel a lot of run out?

The fan is off. I also disconnected the crank sensor and scoped it, same signal

I understand you posted a 'scope graph, but the specifics and span of the traces are not specified so I am assuming a lot, and without detail.

For example, your image in post 63374 shows about 32 pulses. Across 9 seconds I assume those are 32 full crank revolutions (213 rpm average), is that correct? If you zoom in on a pulse, is it one tapered pulse, or two pulses close together? What is the average tooth voltage that the signal conditioner does not see (the other 59)? Most signal conditioners need ±0.2V to reliably register a tooth. A common target for cranking-speed sensor voltage is 1V.

The sensor does not appear to have the correct aperture for the wheel used, so tooth voltage is low, except for the 1st tooth after the gap. Is that what he scope is showing? What is the sensor gap, and is it in-spec? Have you tested different sensor gaps?

hi again!!

I had to put the project on the side, finally today had the time to go over it. Here are all the steps and findings

1. When the trigger was set to Normal Distributor, the RPM was half of what the actual RPM, also when using the timing gun, the TDC changes every time I re-crank the engine, so it wasn't the right solution

2. I had a 36-1 trigger wheel with its own crank sensor rotated by a small motor, connected it to my current setup, adjusted the trigger setup and we got RPM. This step eliminated most suspected issues, used the original crank sensor on the same 36-1 wheel and got RPM.

3. Reconnected my crank sensor back on my engine, set up the software back to 60-2, tried all combination falling/rising edge, nothing. but this time I was able to get the correct scope signal from the crank sensor, before the conditioner, please note that the conditioner LED was blinking the whole time we were cranking the engine...NO RPM!!

4. did not clear the EEPROM yet

attaching the new unconditioned crank signal!

Tomorrow morning, I will clear the EEPROM, reinstall everything, if still no RPM, I will scope input crank signal, conditioned signal, and arduino pin signal!

any help and guidance are highly appreciated

As you are on Missing Tooth decoder, reading the missing teeth is important for sync and resulting rpm. Assuming the probes were connected to + and - correctly, the sensor polarity is reversed. This can interfere with reading the missing teeth for sync properly.

I would swap the sensor wires on the board input and set Trigger Edge for Rising (if MiniMAX-A2 conditioner) or set for Falling (if DSC), as a first step to set baseline configuration.

Finally we got RPM

But the rpm reading is half of what the timing gun is reading

Also when looking at the timing pulley the reading is not constant, as I do not see the same mark every rotation

Please note that spark plugs are removed, thus MAP is not correct